Study On Hummock Wetland Diversity And Contribution To Soil Multifunctionality,Inner Mongolia

Hummock is a typical wetland microtopography,widely distributed in riparian,rivers and river valley wetlands.In recent years,due to climate change and human activities,the wetlands of hummock have been degraded to different degrees,causing the loss of soil multifunctionality in wetlands.There is a lack of basic data on the geographical distribution and biodiversity of hummock wetlands in Inner Mongolia,and the influence of microtopography on soil multifunctionality under different geographical distribution characteristics is not clear.In this study,the spatial distribution pattern and habitat characteristics of the typical hummock wetlands in Inner Mongolia were determined through literature compilation,field survey and microtopography measurement;the soil multifunctionality and its maintenance mechanism were determined through a plant community survey of the hummock wetlands,combined with soil physical and chemical property determination and soil microbial community structure and functional group analysis.The main results are as follows:(1)Hummock wetlands are mainly distributed in the plains and mountainous areas of river floodplains,gullies,oxbow lakes,the edges of depressions and wide valleys of ancient rivers in Inner Mongolia.According to the geomorphic characteristics of the distribution of the hummock wetlands,the hummock wetlands in Inner Mongolia are mainly divided into flowing water landforms,alpine landforms,tundra landforms and lakeside zone landforms.(2)Based on the geomorphological characteristics of the distribution of hummock wetlands combined with vegetation and soil properties,Inner Mongolia hummock wetlands can be classified as alpine hummock wetlands,river hummock wetlands,valley hummock wetlands,riparian hummock wetlands and lakeside hummock wetlands.There are significant differences in the morphology and number of hummock in different types of wetlands,and the volume and surface area of hummock are consistent with the variation of hummock height,all showing oxbow lakes > river headwaters > river valley depressions > riparian > lakeside.The dominant plants in different microtopography were different,and the dominant plants at the hummock were mainly Carex appendiculata,and the dominant plants hollow were Argentina anserina,Carex pediformis,Poa nemoralis,Inula Britannica and Eleocharis valleculosa.The Richness and Shannon indices of plant species in both alpine and lakeside wetlands exhibited higher plant diversity at hummock than hollow,while the opposite was true for other types of wetlands.The variation of plant diversity indices is related to soil physicochemical properties and hummock morphology.(3)The dominant phyla in different microtopography were similar.The dominant phyla of soil bacteria included Proteobacteria,Actinobacteriota and Acidobatcteriota;the dominant phyla of fungi included Ascomycota,unclassified＿k＿Fungi,Basidiomycota and Mortierellomycota.Microtopography altered soil bacterial and fungal microbial diversity,with higher α-diversity of soil bacteria and fungi hollow than at hummock,but did not reach significant differences.The β-diversity of fungi and bacteria in different types of wetlands differed significantly.Soil p H,EC,MBN,AKP,β-GC,AP and plant Pielou index were the main driving forces affecting soil bacterial and fungal community structure.(4)The interactions of bacterial communities were stronger in hummock soils than hollow in alpine wetlands,valley wetlands and riparian wetlands with different microtopography,while fungal communities were weaker than hollow;the interaction of fungi was dominant in hummock soils in lakeside wetlands,while bacterial interactions were dominant hollow.Based on PICRUSt2 function prediction,it was found that soil bacteria in different types of hummock wetlands have strong new city metabolism,and high carbohydrate metabolism and amino acid metabolism in hummock soils indicate higher C and N turnover in hummock soils;fungal function prediction using FUNGuild found that saprophytic fungi are the main functional group except for unclassified functional groups.(5)There are differences in the effects of hummocks and hollow on soil multifunctionality in different types of wetlands.Hummocks in riparian wetlands,river wetlands and valley wetlands significantly increased soil multifunctionality,while hollow in alpine wetlands and lakeside wetlands significantly increased soil multifunctionality.(6)The relationships between aboveground plant diversity and belowground microbial diversity and soil multifunctionality were inconsistent across microtopography.In hummock soils,plant Richness index was significantly and linearly positively correlated with soil multifunctionality,and fungal Sobs index,fungal Shannon index and fungal ACE index were significantly and linearly positively correlated with soil multifunctionality.In hollow soils,plant Richness and plant Shannon index showed significant linear positive correlations with soil multifunctionality,while both hollow bacterial diversity and fungal diversity did not reach significant linear correlations with soil multifunctionality.(7)Microtopography has a greater influence on soil multifunctionality,which not only directly affects soil multifunctionality,but also can affect soil multifunctionality by changing soil moisture.Aboveground plant species richness is the main explanatory factor of soil multifunctionality in hummock wetland.Among subsurface biodiversity,fungal abundance rather than bacterial diversity influenced soil multifunctionality.Also,specific fungal genera closely related to soil multifunctionality were identified,and saprophytic nutrient fungi were particularly important for maintaining multiple soil functions.In summary,above-and below-ground biodiversity,microbial community composition,and soil multifunctionality differed significantly across microtopography in the hummock wetlands of Inner Mongolia.Microtopography and soil moisture jointly drive plant and microbial diversity,which in turn regulates soil multifunctionality.This thesis provides data on the distribution,vegetation and soils of the hummock wetlands in Inner Mongolia,which helps to further deepen the theory of vegetation geography and provides a theoretical basis for the conservation and ecological restoration of the hummock wetland system in mountainous and highland areas.In addition,this thesis enriches the cognitive practice of above-and below-ground biodiversity regulation of soil multifunctionality in wetland ecosystems.